We have previously studied the adhesion of human lymphocytes to surfaces coated with antigen-antibody complexes as a means of studying the killer-target cell interaction during antibody dependent lymphocyte mediated cytotoxicity and as a means of separating cells on the basis of their Fc receptors. We have extended this work to studying the adhesion of human B cells via sIg, using goat anti-human Ig bound to plastic surfaces. Such adhesion can be used to isolate B lymphocytes, leaving lymphocytes bearing high affinity Fc receptors unbound. Tissue culture flasks coated with these ligands can preparatively remove FcR positive sIg negative cells of sIg positive Fcr negative B cells; 25 x 10 to the 6th power cells can be processed per flask. These results confirm previous data that B cells do not have avidly binding Fc receptors.